1. Field of the Invention
This invention generally relates to an electrophotographic copying apparatus, and, in particular, to a color copier which employs a plurality of photosensitive drums for transferring color-separated toner images to a transfer medium to obtain a reproduced color image.
2. Description of the Prior Art
A color copier using a plurality of photosensitive drums for different color-separated images is well known in the art. In such a prior art color copier, after forming toner images of different colors on respective photosensitive drums, the drums are driven to rotate in the reversed direction and, at the same time, a sheet of transfer paper is transported by means of a transfer belt in the same direction as the forward moving direction of an original holder, whereby the toner images different in color are transferred to the sheet of transfer paper one after another in sequence thereby producing a color copy of an original image. However, in the prior art color copier, since the direction of rotation of the photosensitive drums is reversed, fluctuations in load are produced in a driving system, which, in turn, would cause mismatching or positional discrepancy between color-separated images. Since a transfer belt is provided for each of the plurality of photosensitive drums and the transfer belts are individually driven to run, fluctuations in load are also produced during transfer of image, which also would cause the color-separated images to be misaligned when superposed one on top of another on the same sheet of transfer paper.